Answers
1: future magic
2: future magic

But yes, that fireball would be spectacular even if the ship could somehow survive.

This is a mod.

In the original game, flight is limited to space and is very arcade-y. Press ‘W’ to activate thrusters and move forward.

KSP, Flight of Nova, Elite: Dangerous - there are plenty sims out there catering to those who want realism.

I think that forcing a completely realistic re-entry would be a bit much for most players, though it would be awesome for the option to be available to those who want a hardcore experience.

At the end of the day, most games are more enjoyable when you suspend disbelief. This is a game where people wear spacesuits in a vacuum, get shot multiple times with blood effects, and carry on fighting without experiencing violent depressurization.

It's a shitty game that makes no sense.

Starfield is more an 'Open World' rpg. Exploration on foot with fight and quest is more prominent than exploration in space. The space part is more like a mean to travel between planet where you could find quest. Sometimes, there's a space fight, or boarding other ship/station. But ship simulation isn't the purpose of this game. You can still build a ship, but you're more focused on look than : 'Will it work ?'.

As a Flight of Nova player, I just saw death. Yes, this is extremely unrealistic, approaching a planet at that speed you'd just vaporize as soon as you hit the atmosphere. It looks like a tiny planet, though, which wouldn't have enough gravity for a thick atmosphere. Probably just scaled down, like Kerbin, which is smaller than Charon.